pandas-dev/pandas · error · ValueError

You must specify at least 4 characters when resetting…

Error message

You must specify at least 4 characters when resetting multiple keys, use the special keyword "all" to reset all the options to their default value

What it means

Raised by `reset_option` as a safety guard: when the pattern matches MORE than one key AND the pattern is shorter than 4 characters AND it is not the special keyword `'all'`. This prevents accidentally resetting a large set of options with a tiny pattern (e.g. `'max'` hits many options).

Solutions

1. Lengthen the pattern to at least 4 characters that still match the intended set, e.g. `pd.reset_option('display')`.
2. Reset each option individually by its full key.
3. Use `pd.reset_option('all')` to reset absolutely every option (intended nuclear option).

Example fix

# before
pd.reset_option('max')   # ValueError: must specify >= 4 chars

# after
pd.reset_option('display.max_rows')
# or, to reset everything:
pd.reset_option('all')

import pandas as pd
from pandas._config.config import _select_options
def safe_reset(pat: str):
    keys = _select_options(pat)
    if len(keys) > 1 and len(pat) < 4 and pat != 'all':
        # caller used a dangerously short multi-match; pick full keys instead
        for k in keys:
            pd.reset_option(k)
    else:
        pd.reset_option(pat)

def is_safe_reset_pattern(pat: str) -> bool:
    import pandas._config.config as c
    keys = c._select_options(pat)
    return not (len(keys) > 1 and len(pat) < 4 and pat != 'all')

try:
    pd.reset_option(pat)
except ValueError as e:
    if 'at least 4 characters' in str(e):
        # lengthen pattern or reset each key individually
        ...
    raise

When it happens

Trigger: `pd.reset_option('max')`, `pd.reset_option('di')`, or any sub-4-char pattern that matches multiple options (and is not exactly `'all'`).

Common situations: Trying to batch-reset a namespace with a short prefix; assuming `reset_option` accepts partial names the way `set_option` does without the guard.

Related errors

• Pattern matched multiple keys
• is a python keyword
• is not a valid identifier
• Must provide an even number of non-keyword arguments
• No such keys(s) for

AI-assisted analysis of pandas-dev/pandas@3b7651241d (2026-08-11). Data as JSON: /api/errors/6df38e80972c6d19. Report an issue: GitHub.

Appendix: source

Thrown at pandas/_config/config.py:392

    set_option : Set the value of the specified option or options.
    describe_option : Print the description for one or more registered options.

    Notes
    -----
    For all available options, please view the
    :ref:`User Guide <options.available>`.

    Examples
    --------
    >>> pd.reset_option("display.max_columns")  # doctest: +SKIP
    """
    keys = _select_options(pat)

    if len(keys) == 0:
        raise OptionError(f"No such keys(s) for {pat=}")

    if len(keys) > 1 and len(pat) < 4 and pat != "all":
        raise ValueError(
            "You must specify at least 4 characters when "
            "resetting multiple keys, use the special keyword "
            '"all" to reset all the options to their default value'
        )

    for k in keys:
        set_option(k, _registered_options[k].defval)


def get_default_val(pat: str) -> Any:
    key = _get_single_key(pat)
    opt = _get_registered_option(key)
    assert opt is not None
    return opt.defval


class DictWrapper:
    """provide attribute-style access to a nested dict"""

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